Metal working fluid composition for use as spray in mist form

ABSTRACT

A metal working fluid composition for use as a spray in the mist form, which comprises (a) a base oil comprising at least one of mineral oils and synthetic oils and, based on an amount of an entire composition, (b) 1 to 50% by mass of a sulfur-based extreme pressure agent and (c) 0 to 30% by mass of an ester of a carboxylic acid and a process for metal working which comprises supplying the metal working fluid composition in the mist form. The metal working fluid is inexpensive and exhibits the excellent property for working.

TECHNICAL FIELD

[0001] The present invention relates to a metal working fluid composition for use as a spray in the mist form and a process for metal working. More particularly, the present invention relates to a metal working fluid composition for use as a spray in the mist form in metal working such as cutting, grinding, rolling, drawing and forging and a process for metal working using the composition.

BACKGROUND ART

[0002] As the metal working fluid, in general, a fluid not soluble in water which is obtained by adding various additives to mineral oils or a fluid soluble in water which is obtained by adding various additives to mineral oils and synthetic oils and used after being diluted with water, is used. In recent years, it is required that the amount of waste fluids be decreased due to the environmental problems and the consumption of electric power be decreased. Therefore, processes for metal working using fluids in the mist form are studied. Since the mist is discharged into the atmosphere when the metal working fluid is used in the mist form, various biodegradable fluids are proposed. For example, processes using biodegradable plant oils as the metal working fluid are disclosed in Japanese Patent Application Laid-Open Nos. Heisei 10(1998)-86036 and Heisei 11(1995)-246881. However, these oils are more expensive than mineral oils and synthetic oils and the workability needs improvement. Therefore, a metal working fluid composition for use as the spray in the mist form which is inexpensive and exhibits excellent workability is desired.

[0003] In Japanese Patent Application Laid-Open No. 2001-49279, a process for working metal materials using a specific methacrylate-based polymer as an additive is disclosed. However, since the diameter of the mist increases due to the addition of the methacrylate-based polymer, the mist forms droplets inside the piping and the formed droplets are attached to the piping to decrease the efficiency of spraying.

[0004] The present invention is made to overcome the above drawbacks and has an object of providing a metal working fluid composition for use as a spray in the mist form which is inexpensive and exhibits excellent workability and a process for metal working using the composition.

DISCLOSURE OF THE INVENTION

[0005] As the result of extensive studies by the present inventors, it was found that the object of the present invention can be effectively achieved by adding a sulfur-based extreme pressure agent and, where necessary, an ester of a carboxylic acid to a base oil. The present invention has been completed based on this knowledge.

[0006] The present invention can be summarized as follows:

[0007] (1) A metal working fluid composition for use as a spray in a mist form, which comprises (a) a base oil comprising at least one of mineral oils and synthetic oils and, based on an amount of an entire composition, (b) 1 to 50% by mass of a sulfur-based extreme pressure agent and (c) 0 to 30% by mass of an ester of a carboxylic acid;

[0008] (2) A metal working fluid composition for use as a spray in a mist form described in (1), which comprises 50 to 90% by mass of component (a) based on the amount of an entire composition;

[0009] (3) A metal working fluid composition for use as a spray in a mist form described in any one of (1) and (2), wherein component (b) comprises at least one of dihydrocarbyl polysulfides and sulfurized oils and fats;

[0010] (4) A metal working fluid composition for use as a spray in a mist form described in any one of (1) to (3), wherein component (c) is at least one of oils, fats and triglycerides which are not oils or fats; and

[0011] (5) A process for metal working which comprises supplying a metal working fluid composition for use as a spray in a mist form described in any one of (1) to (4) in a mist form.

THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION

[0012] The present invention will be described specifically in the following.

[0013] As the base oil of component (a) constituting the metal working fluid composition for use as a spray in the mist form of the present invention, a mineral oil, a synthetic oil or a mixture of these oils can be used. The mineral oil and the synthetic oil are not particularly limited as long as these oils are used as the base oil for metal working fluids. It is preferable that the mineral oil and the synthetic oil have a kinematic viscosity at 40° C. in the range of 1 to 100 mm²/s and more preferably in the range of 3 to 50 mm²/s. When the kinematic viscosity exceeds the above range, there is the possibility that the mist is not formed. When the kinematic viscosity is smaller than the above range, the workability becomes poor due to great volatility, and there is the possibility that the workability such as the property for cutting cannot be maintained. The pour point which is the index of the fluidity of the base oil at low temperatures is not particularly limited. It is preferable that the pour point is −10° C. or lower.

[0014] Various types of mineral oil and synthetic oil can be used as the base oil. The base oil can be suitably selected from these oils in accordance with the application. Examples of the mineral oil include distilled oils obtained by atmospheric distillation of paraffinic crude oils, intermediate crude oils and naphthenic crude oils, distilled oils obtained by vacuum distillation of residual oils of the atmospheric distillation and purified oils obtained by purifying the above oils in accordance with a conventional process such as oils purified with solvents, oils purified by hydrogenation, oils treated by dewaxing and oils treated with clay.

[0015] Examples of the synthetic oil include poly-α-olefins, α-olefin copolymers, polybutene, alkylbenzenes, esters of polyols, esters of dibasic acids, polyoxyalkylene glycols, esters of polyoxyalkylene glycols, ethers of polyoxyalkylene glycols and silicone oils.

[0016] These base oil may be used singly, in combination of two or more or in combination of mineral oils and synthetic oils.

[0017] It is preferable that the amount of component (a) in the metal working fluid composition is in the range of 50 to 98% by mass based on the amount of the entire metal working fluid composition. When the amount of the base oil is less than the above range, there is the possibility that the mist is not formed. When the amount exceeds the above range, there is the possibility that the workability such as the property for cutting cannot be maintained.

[0018] The sulfur-based extreme pressure agent of component (b) constituting the metal working fluid composition for use as a spray in the mist form of the present invention is not particularly limited as long as the agent has a sulfur atom in the molecule and can be dissolved or uniformly dispersed in the base oil of the lubricating oil so that the effect of the extreme pressure agent can be exhibited. Examples of the sulfur-based extreme pressure agent include sulfurized oils and fats, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiocarbamates, thioterpenes and dialkyl thiodipropionates. The sulfurized oils and fats are obtained by the reaction of sulfur or compounds having sulfur with oils and fats such as lard, whale oil, plant oils and fish oils. The content of sulfur is not particularly limited. In general, it is preferable that the content of sulfur is in the range of 5 to 30% by mass. Examples of the sulfurized oil and fat include sulfurized lard, sulfurized rapeseed oil, sulfurized castor oil, sulfurized soy bean oil and sulfurized rice bran oil. Examples of the sulfurized fatty acid include sulfurized oleic acid. Examples of the sulfurized ester of a fatty acid include sulfurized methyl oleate and sulfurized octyl ester of rice bran fatty acid.

[0019] Examples of the sulfurized olefin include compounds represented by the following general formula (1):

R¹—S_(x)—R²   (1)

[0020] wherein R¹ represents an alkenyl group having 2 to 15 carbon atoms, R² represents an alkyl group or alkenyl group having 2 to 15 carbon atoms, and x represents an integer of 1 to 8. This compound can be obtained by the reaction of an olefin having 2 to 15 carbon atoms, or a dimer, a trimer or a tetramer thereof with a sulfurizing agent such as sulfur and sulfur chloride. As the olefin, propylene, isobutene and diisobutene are preferable.

[0021] The dihydrocarbyl polysulfide is a compound represented by the following general formula (2):

R³—S_(y)—R⁴   (2)

[0022] wherein R³ and R⁴ each represent an alkyl group or cyclic alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms or an arylalkyl group having 7 to 20 carbon atoms and may represent the same group or different groups, and y represents an integer of 2 to 8. When R³ and R⁴ represent alkyl groups, the above compound is called a sulfurized alkyl.

[0023] Examples of the group represented by R³ and R⁴ in the above general formula (2) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, various types of pentyl group, various types of hexyl group, various types of heptyl group, various types of octyl group, various types of nonyl group, various types of decyl group, various types of dodecyl group, cyclohexyl group, cyclooctyl group, phenyl group, naphthyl group, tolyl group, xylyl group, benzyl group and phenetyl group.

[0024] Examples of the dihydrocarbyl polysulfide include dibenzyl polysulfide, di-tert-nonyl polysulfide, didodecyl polysulfide, di-tert-butyl polysulfide, dioctyl polysulfide, diphenyl polysulfide and dicyclohexyl polysulfide.

[0025] Examples of the thiocarbamate include zinc dithiocarbamate. Examples of the thioterpene include reaction products of phosphorus pentasulfide and pinene. Examples of the dialkyl thiodipropionate include dilauryl thiodipropionate and distearyl thiodipropionate.

[0026] Among these substances, dihydrocarbyl polysulfides, sulfurized fats and oils and mixtures of these substances are preferable from the standpoint of the properties as the extreme pressure agent.

[0027] In the present invention, component (b) described above may be used singly or in combination of two or more. The amount of component (b) is in the range of 1 to 50% by mass and preferably in the range of 3 to 30% by mass based on the mass of the entire composition. When the amount is less than 1% by mass, the workability such as the property for cutting cannot be maintained. When the amount exceeds 50% by mass, viscosity of the composition increases and the effect of the present invention cannot be obtained.

[0028] Where necessary, the metal working fluid composition for use as a spray in the mist form of the present invention may further comprise an ester of a carboxylic acid as component (c) so that the workability is improved. The ester of a carboxylic acid has at least one ester linkage (—CO₂—) in the molecule and includes monoesters of carboxylic acids having one ester linkage and esters of carboxylic acids having two or more ester linkages.

[0029] The monoester having one ester linkage is a compound represented by R⁵—CO₂—R⁶, wherein R⁵ and R⁶ each represent an alkyl group or an alkenyl group. Examples of the group represented by R⁵ include n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, 2-methyldecyl group, 3-methyldecyl group, 4-methyldecyl group, 5-methyldecyl group, 6-methyldecyl group, 7-methyldecyl group, 9-methyldecyl group, 6-ethylnonyl group, 5-propyloctyl group, 3-methylundecyl group, 6-propylnonyl group, 2-methyldodecyl group, 3-methyldodecyl group, 4-methyldodecyl group, 5-methyldodecyl group, 11-methyldodecyl group, 7-propyldodecyl group, 2-methyltridecyl group, 12-methyltridecyl group, 2-methyltetradecyl group, 4-methyltetradecyl group, 13-methyltetradecyl group, 14-methylpentadecyl group, 2-ethylhexadecyl group, 14-ethylhexadecyl group, 14-ethylheptadecyl group, 15-ethylheptadecyl group, 16-ethylheptadecyl group, 2-butyltetradecyl group, 2-methyloctadecyl group, 3-methyloctadecyl group, 4-methyloctadecyl group, 5-methyloctadecyl group, 6-methyloctadecyl group, 7-methyloctadecyl group, 8-methyloctadecyl group, 9-methyloctadecyl group, 10-methyloctadecyl group, 11-methyloctadecyl group, 14-methyloctadecyl group, 15-methyloctadecyl group, 16-methyloctadecyl group, 17-methyloctadecyl group, 15-ethylpentadecyl group, 9-decenyl group, 10-undecenyl group, 11-octadecenyl group, 9-eicosenyl group, 11-eicosenyl group, 11-docosenyl group, 13-docosenyl group and 15-tetradocosenyl group.

[0030] Examples of the group represented by R⁶ include the groups described above as the examples of the group represented by R⁵, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-eicosyl group, 2-methylpentyl group, 3-methylpentyl group, 4-propylpentyl group, 4-ethylpentyl group, 3-methylnonadecyl group and 2-ethyloctadecyl group.

[0031] Examples of the ester having two or more ester linkages include esters of oxalic acid, esters of malonic acid, esters of succinic acid, esters of maleic acid, esters of fumaric acid, esters of glutaric acid, esters of adipic acid, esters of pimellic acid, esters of suberic acid, esters of azelaic acid, esters of sebacic acid, esters of phthalic acid, esters of trimellitic acid, esters of pyromellitic acid, oils and fats (soy bean oil, rapeseed oil, lard and the like), triglycerides which are not oils or fats, esters of neopentyl glycol, esters of trimethylolpropane and esters of pentaerythritol. Examples of the alcohol for the above esters of acids include alcohols having groups represented by R⁶ described above. Examples of the acid for the above ester of alcohols include acids having groups represented by R⁵ described above.

[0032] Among the above substances, oils and fats, triglycerides which are not oils or fats and mixtures of these substances are preferable since the workability is improved.

[0033] In the present invention, component (c) described above may be used singly or in combination of two or more. The amount of component (c) is in the range of 0 to 30% by mass and preferably in the range of 5 to 20% by mass based on the amount of the entire composition. When the amount exceeds 30% by mass, the effect of the extreme pressure agent is adversely affected and the workability becomes poor.

[0034] The metal working fluid composition for use as a spray in the mist form of the present invention can be obtained by mixing the base oil with component (b) described above and, where necessary, component (c) described above. In general, various conventional additives may be suitably added in the range such that the object of the present invention is not adversely affected so that the basic properties of the composition as the metal working oil are maintained. Examples of the additive include extreme pressure agents other than the sulfur-based extreme pressure agents, oiliness agents, defoaming agents and antioxidants. Mist preventives which adversely affect the formation of the mist, additives containing metals which are hardly formed into the mist and additives having a great molecular weight cannot be used as the additives since there is the possibility that the formation of the mist becomes difficult or the effective component cannot be formed into the mist.

[0035] As the second aspect of the present invention, the present invention provides the process for metal working which comprises supplying the metal working fluid composition for use as a spray in the mist form described above in the mist form. This process provides excellent workability.

EXAMPLE

[0036] The present invention will be described more specifically with reference to examples in the following. However, the present invention is not limited to the examples.

Examples 1 to 6 and Comparative Examples 1 to 6

[0037] Components were mixed with a base oil in relative amounts shown in Table 1 and cutting oil compositions of Examples and Comparative Examples were prepared. Using the prepared oils, cutting (cutting of the outer periphery of a round rod) was conducted under the condition shown in the following and the maximum cutting force and the roughness of the cut surface were evaluated. The results are shown in Table 1.

[0038] Conditions of Cutting

[0039] (1) Speed of cutting: 10 m/minute

[0040] (2) Moving speed of the rod: 0.05 mm/rev

[0041] (3) Amount of cutting: 2.0 mm

[0042] (4) Material for cutting: a material in accordance with the Japanese Industrial Standard S45C having a pillar shape having an outer diameter of 35 mm

[0043] (5) Tool for cutting: a tool in accordance with the Japanese Industrial Standard SKH51 (the rake angle in the transverse direction: 15°; the clearance angle in the transverse direction: 1°)

[0044] (6) Amount of supplied oil: 10 ml/hr (supplied in the mist form)

[0045] (7) Time of cutting: 3 minutes TABLE 1 Example Comparative Example 1 2 3 4 5 6 1 2 3 4 5 6 Relative amounts of components (% by mass) base oil*¹ 95 90 85 80 85 80 100 — — — 80 80 polysulfide*² 5 — 5 — 5 5 — — — — — — sulfurized oil and fat*³ — 10 — 10 — 5 — — 5 — — — oil and fat*⁴ — — 10 10 — 10 — 100 95 90 20 — methyl stearate — — — — 10 — — — — 10 — 20 Evaluation cutting force (maximum value) (N) 362 372 358 352 348 325 1165 425 615 553 762 849 roughness of cut surface (Rz) (μm) 5.5 5.8 4.8 5.5 4.9 5.1 21.8 7.5 7.4 6.5 15.8 16.3

[0046] Industrial Applicability

[0047] In accordance with the present invention, the metal working fluid composition for use as a spray in the mist form which is inexpensive and exhibits excellent workability and the process for metal working using the composition can be provided. 

1. A metal working fluid composition for use as a spray in a mist form, which comprises (a) a base oil comprising at least one of mineral oils and synthetic oils and, based on an amount of an entire composition, (b) 1 to 50% by mass of a sulfur-based extreme pressure agent and (c) 0 to 30% by mass of an ester of a carboxylic acid.
 2. A metal working fluid composition for use as a spray in a mist form according to claim 1, which comprises 50 to 90% by mass of component (a) based on the amount of an entire composition.
 3. A metal working fluid composition for use as a spray in a mist form according to claim 1, wherein component (b) comprises at least one of dihydrocarbyl polysulfides and sulfurized oils and fats.
 4. A metal working fluid composition for use as a spray in a mist form according to claim 1, wherein component (c) is at least one of oils, fats and triglycerides which are not oils or fats.
 5. A process for metal working which comprises supplying a metal working fluid composition for use as a spray in a mist form described in claim 1 in a mist form. 